Employers’ policies determine if employees will be paid or unpaid and they can require that employees use any and all paid time off concurrently with FML.

Under the regulations, all forms of paid leave offered by an employer will be treated the same, regardless of the type of leave substituted. An employer may choose to require paid leave run concurrently with FML . The statute provides that employees may choose to take annual, personal, sick leave concurrently with FMLA. Employers can require their employees to take paid leave concurrently with FML, and may elect to adopt policy mandating the order of use.

Leave that qualifies as FML must be charged against the employee's FML entitlement (Dept. of Labor, Wage and Hour Division (DOL WHD) opinion FMLA2019-1A.)

A city may not choose to 'stack' leave (example: An employee takes five weeks off for surgery and uses all of his available sick leave. The employer does not start FMLA protection until the employee runs out of sick leave, which means the employee will get five weeks sick leave and then the employer will start 12 weeks of FML when the employee is out of sick leave.) This is impermissible according to the DOL WHD.